Fan inlet guard and a method of manufacturing the same



June 18, 1935 M. c. ALUN 2,005,408

FAN INLET GUARD AND A METHOD OF MANUFACTURING THE SAME Fil ed Feb. 21,1955 I 28F, /6, Z INVEYNTOR L7 MATTHEW C1 ALLJN ATTORNEY Patented June18, 1935 FAN INLET GUARD AND A METHOD OF MANUFACTURING SAME Matthew'C.-Allin, Weston, Ontario, Canada,- assignor to Riley. Engineering &Supply Co. Ltd., Toronto, Ontario, Canada, a corporation of CanadaApplication February 21, 1933, Serial No. 657,824

8 Claims.

' Thisinv ention relates to a fan inlet guard and a method ofmanufacturing the same, the construction beingadapted to admit air tothe interior of a fan housing, to protect the operator from injury, andto prevent foreign bodies from entering the fan and damaging therotatingfan wheel.

It has been the practice heretofore to mount screens over the air inletsof fans, but the prior constructions have been expensive to manufacture,and it has been difficult toprovicle the desi'rable stream-lined airpassage without complicating the construction and adding considerably toits cost. Furthermore, prior arrangements were lacking in strength andwere frequently, distorted or broken and rendered unsightly byaccidental blows. It is accordingly one object of the invention toprovide a fan inlet guard which is simple and inexpensive tomanufactureand which is very strong in proportion to its weight.

- It is a further object of the invention to provide a' fan inlet guardwhich is attractive in appearance, andwhich .will lead the air smoothlyand gradually into the center of the fan wheel without producingundesirableeddy currents in the airstream.

Itfisa' further object of the invention to provide a method ofmanufacturing fan inlet guards, which is simple and inexpensive to carryout in practice.

It is a further object of the invention to provide a method ofmanufacturing fan inlet guards which will produce a substantiallyintegral and 35 very strong construction.

With these and other objects in view, as will be apparent to thoseskilled in the art, the invention resides in the combination of partsand the steps of the process set forth in the specification 4 andcovered by the claims appended hereto.

In accordance with my invention I provide a fan inlet guard comprising aperforated screen, preferably of wire-mesh, having its peripheralportion embedded in a cast metal frame. In the preferred construction,the frame is circular, and the screen is dished outwardly. The frame maybe shaped to provide an inwardly-tapering stream-lined air passage. Theconstruction is 50 manufactured by first providing a screen and thencasting the metal frame into engagement with the peripheral portion ofthe screen. The screen is preferably dished before the castingoperation, and it may be embedded in a core with the peripheral portionof the screen projecting outwardly beyond the core, molten metal beinpoured around the core to form the frame.

Referring to the drawing illustrating one embodiment of the invention,and in which like reference numeralsindicate like parts, V

Fig. 1 is a side elevation of a fan showing my improved inlet guardapplied thereto;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a partial sectional view of a core box; and

Fig. 4 is a section through a mold ready for the pouring operation.

The embodiment illustrated comprises a fan housing It] provided with theusual scroll-shaped peripheral wall, and having a rotatable fan wheel l2of well-known construction mounted therein. An inlet opening M (Fig, 2),preferably circular in shape, isprovided in the side wall of the housingill to admit air to the fan wheel l2.

In order to prevent foreign bodies from reaching the fan wheel, and alsoguide the air into the interior of the wheel, I provide a perforatedscreen l6 havingits'peripheral portion embedded in a cast metal frameIT. The screen I6 is preferably circular in shape and formed of a rathercoarse wire-mesh fabric. The frame I! is shown provided with an annularflange l8 which is riveted or otherwise secured to the fan housing Insurrounding the opening M. The frame I! projects inwardly through thisopening, and tapers smoothly and gradually towards the fan wheel to forma stream-lined air'passage. The screen I6 is dished outwardly, and hencehas great strength to resist accidental blows.

In the manufacture of my improved fan inlet guard, I first provide thescreen l6 and then cast the frame I! into engagement with the peripheralportion thereof. The screen is preferably bent into a dished shapeprior. to the casting operation, by means of dies or. in any othersuitable way.

In Fig. 3 I have shown a partial section through a core box which may beconveniently utilized in carrying out my novel process. This core boxcomprises a lower part 20 and an upper part 2|, these parts being shapedto provide the desired stream-lined form for the interior surface of thecast frame. An annular groove 22 is provided between the parts 20 and2|, and in making the core the peripheral portion of the screen I6 isplaced in this groove and the remainder of the screen is embedded in thecore sand. Thus, when the core is completed, the peripheral portion ofthe screen will project outwardly beyond the core. It will be noted thatthe maximum internal diameter of the core box occurs intermediate theheight of the upper part 2|, so that it will be necessary to form thispart in a plurality of sections and withdraw each section in a radialdirection, as will be understood by those skilled in the art.

Afterthc coreis completed it is placed in a mold and the frame I! iscast aroundthe core. In Fig. 4 I have shown a section through a moldready for the casting operation. This mold, which may be prepared inaccordance with the usual and well-known foundry practice, comprises acope 24 and a drag 25 supported on a bottom board 25. The core 28,withithe screen:1i6-.embedded therein, is located in the moldobetweenthe cope and the drag, and an'annular moldcavity 29 surrounds the core.The peripheral portion of the screen projects into thiscavity. The moldis provided with the usual gate 3|, sprue 32, and pouring basin 33.Molten metal, such as iron, is poured into the mold to fillthe cavity 29and form the annular frame I1. As this metalsolidifies it provides afirm and'substantially integral joint with the screen IS. The frame I!will shrink appreciably as it cools, and this shrinkage will simplycause the dishing of the screen to, be slightly more pronounced. Therewill be no buckling or irregular distortion of the screen, as would bethe case if the screen were originally flat.

It will now be apparent that I have provided a fan inlet guard which issimple and inexpensive to manufacture and effective for the purposeintended. The construction is attractive in appearance, and provides asmooth stream-lined passageto conduct air into the fan wheel. Theintegral bond between the cast frame and the screen, together with thearched or dished form of the screen, provides. great strength withoutexcessiveweight. Consequently the screen: will withstand'comparativelyheavy blows withoutinjury ordistortion. My improved process ofmanufacture is simple and requires no expensive equipment. -It1 can bereadily understood and-carried out 'by workmenof'ordinary skill in thefoundry art.

"-Havingthus described myinvention, what I claim asnew' and desire tosecure by Letters Patent is:

1; A fan inletguard comprising a dished circular wire-mesh screen havingits peripheral portion embedded in an annular cast metal frame.

2. A fan inlet guard comprising an outwardly dished circular wire-meshscreen having its peripheral portion embedded in an annular cast metalframe, the frame being shaped to provide an inwardly-taperingstream-lined air,- passage.

3. A fan inlet guard comprising a dished circular wire-mesh screenhaving its peripheral portion embedded in an annular cast metal frame,the frame having an integral annular flange shaped to;engage the wall ofa fan housing.

4. The method of manufacturing a fan inlet guard comprisingthe steps ofproviding a substantially circular wire-mesh screen, bending the screeninto a dished shape, and casting an annular metal frame into engagementwith the peripheral portion of the screen.

5. The method of manufacturing a fan inlet guard comprising the steps ofproviding a substantially circular wire-mesh screen, bending the screeninto a dished shape, embedding thedished screen in a core with theperipheral. portionof the screen. projecting outwardly beyond the core,

placing the core in. a.mold.having an. annular cavity surrounding thecore,.and .pouringmolten metal into the cavity to form an annular framefirmly united withthe screen.

6. A fan inlet guardcomprising anannular frame and a wire-meshscreen.extending. across the opening in the frame, the ends of the wiresforming the screen beingembedded in they material of the frame, and thescreen. being dished to relieve stresses caused byv temperature changesand to increase the strengthof the-screen.

7. A' fan inlet guard comprising an annular frame shaped to provideaninwardly-tapering stream-lined air passage, and a wire-mesh screenextending across the passage, the endsof the wires forming the screenbeing embeddedinthe material of the frame, and the screenbeing dishedoutwardly to relieve stresses causedloy temperature changes and toresist external blows.

8. A fan inlet guard comprising anannular frame having an integral.annular flange. shaped to engage the wall of a fan housing, anda.d.ished wire-mesh screen extending across ,theopening in the frame,the ends of thewiresformingthe screen being embedded in the material ofthe frame.

MATTHEW C. ALLIN.

